Networks

1
Networks

• Binit Mohanty
• Ketan Rajawat

2
Recap Layered Architecture

• Application layer for GUI
• Transport layer for Reliability
• Networking layer for routing
• MAC layer for Media access control
• Physical layer for modulation

3
Ethernet

• Used in IITK
• LAN
• One medium - many users
• IP address and Names - the DNS server
• CSMA/CD Carrier Sense Multiple Access with
  Collision Detection

4
Internetworking

• Eg Connecting many LANs
• Each Network has Routers
• Routers run some programs for finding the best
  path
• Data in form of packets appended with source and
  destination address
• Forwarded according to routing table

5
TCP Transport Layer

• Limitations of PHY layer
• Packets are lost, reordered, duplicated
• Congestion, overflow
• Solution TCP
• Reliability by ACKs
• Numbering of packets
• Limit transfer rate according to congestion

6
TCP Connection Establishment

• Called a connection oriented protocol as opposed
  to a best effort protocol

7
TCP Slow Start
8
TCP Close Connection
9
TCP

• When would one not want TCP ?
• When would reliability be at a lower priority ?
• Streaming Data streaming video
• Energy efficiency Sensor Networks

10
GSM Global System for Mobile
11
GSM channels

• Channels comprising of frequencies and time slots
• Broadcast channel network identity, frequency
  of operation
• Control Channels signal power, channel estimate,
  timing estimate, call origination
• Traffic channels for voice